screw drive

Abstract

A screw head bushing (2) for a screw (1), the screw head bushing (2) having an outer portion (3) and an inner portion (4) continuous with the outer portion (3), the outer portion (3) having a larger diameter (D) than the inner portion (4), the outer portion (3) being configured essentially as a truncated cone tapering toward the inner portion (4), the inner portion (4) being configured as an engaging shape for rotatably and securely receiving a screw head drive (6).

Description

[Technical Field]

[0001] The present invention relates to a screw head bushing for a screw according to the preamble of claim 1, a screw head drive according to the preamble of claim 6, a forming tool for forming a screw head bushing according to the preamble of claim 11, a screw according to the preamble of claim 16, and a kit comprising a screw and a screw head drive. [Background technology]

[0002] A screw head bushing is a geometric structure formed within a screw head and intended to rotatably and securely accommodate a screw head drive. Torque can be transmitted to the screw using the screw head drive to drive the screw into or out of a material. Several shapes for screw head drives and screw head bushings are known in the prior art, such as Phillips, slot, or Torx shapes. These shapes are often referred to as screw drives. Shapes such as Torx shapes are optimized for transmitting high torque from the screw head drive to the screw head bushing.

[0003] A drawback of many screw drives is that in the case of an insufficiently centered orientation (e.g., an oblique orientation) of the screw head drive relative to the screw head bushing, a poor form fit between the screw head drive and the screw head bushing can be established, resulting in the screw head drive slipping within the screw head bushing. This can lead to damage to the screw head bushing and / or the screw head drive, which can then no longer transmit the torque required to screw in or unscrew the screw provided with the screw head drive. This can also make it impossible to screw the respective screw into or out of the material using simple means, which can damage or impair the function of the workpiece into which the screw is screwed.

[0004] A shape for improving the orientation of a screw head drive within a screw head bushing is known in the prior art as the TTAP screw drive, disclosed as U.S. Pat. No. 6,951,158 B1. The screw head bushing of the TTAP screw drive includes an outer portion and an inner portion, and the inner portion includes a centering cone. In this way, the screw head drive is centered within the screw head bushing. Summary of the Invention [Problem to be solved by the invention]

[0005] The invention is based on the problem of providing an alternative geometry for the screw drive which ensures high torque transmission and also allows centering of the screw head drive in the screw head bushing.

[0006] According to the present invention, this problem is solved by a screw head bushing having the features of claim 1, a screw head drive having the features of claim 6, a forming tool for forming the screw head bushing having the features of claim 11, a screw having the features of claim 16, and a kit comprising a screw and a screw head drive having the features of claim 17. [Means for solving the problem]

[0007] An embodiment of a head bushing for a screw according to the present invention includes an outer portion and an inner portion adjacent to the outer portion. The outer portion has a larger diameter than the inner portion along at least a first axis oriented perpendicular to the depth of the head bushing and is essentially configured as a truncated cone tapering toward the inner portion. The inner portion is configured as an engagement shape for rotatably and securely receiving a head drive. The conically tapering outer portion forms a guide for the head drive, thereby preventing the head drive from being inserted into the head bushing at an angle. Furthermore, the inner portion embodied as an engagement shape is located behind the outer portion or at a greater depth than the outer portion, respectively, thereby ensuring that the head drive is oriented so that it is centered by the outer portion before engaging the engagement shape. In this way, wear of the engagement shape due to an improperly inserted head drive is prevented.

[0008] The outer part preferably comprises a truncated conical shell inclined at an angle of 2.5° to 10° relative to the cylindrical shell, which has the advantage that the screw head drive, which is installed at an angle, can be centered without great effort.

[0009] Furthermore, the screw head bushing of the present invention according to a preferred embodiment comprises an insertion region disposed between the outer and inner parts and having an insertion surface, the insertion surface being inclined essentially by 10° relative to the truncated cone base region of the outer part, thereby facilitating the sliding of the contact profile of the screw head drive into the engagement profile of the screw head bushing.

[0010] The engagement geometry of the screw head bushing according to the present invention is preferably a Phillips, Torx or slot shape. Particularly preferably, the engagement geometry is a slot shape that is oriented perpendicular to the depth of the screw head bushing and penetrates the screw head bushing in a second axis different from the first axis. In this way, it is possible to advantageously use a number of different screw drive geometries within the scope of the present invention.

[0011] The head drive according to the present invention includes an outer portion and an inner portion adjacent to the outer portion, the inner portion having a larger diameter than the outer portion along at least a first axis oriented perpendicular to the height of the head drive. The inner portion is configured essentially as a truncated cone tapering toward the outer portion, the outer portion including a contact feature configured to rotatably and securely engage with an engagement feature of the head bushing. The conically tapering inner portion of the head drive forms a guide that prevents the contact feature of the head drive from being inserted obliquely into the engagement feature of the head bushing.

[0012] The inner part of the screw head drive according to the invention preferably comprises a truncated conical shell inclined at an angle of 2.5° to 10° relative to the cylindrical shell, thus providing the advantage that the screw head drive, which is installed at an angle, can be centered without great effort.

[0013] The head drive of the present invention is arranged between the outer and inner parts and comprises an insertion region with an insertion surface, which is inclined essentially by 10° relative to the frusto-conical base region of the inner part, thereby facilitating the sliding of the contact profile of the head drive into the engagement profile of the head bushing.

[0014] The contact geometry of the screw head bushing according to the invention is preferably a Phillips, Torx or slot geometry. Particularly preferably, the contact geometry is a slot geometry that is oriented perpendicular to the height of the screw head drive and penetrates the screw head drive in a second axis different from the first axis. In this way, it is possible to advantageously use a number of different screw drive geometries within the scope of the invention.

[0015] The forming tool according to the present invention for forming a screw head bushing in a screw head includes an outer portion and an inner portion adjacent to the outer portion, the inner portion having a larger diameter than the outer portion along at least a first axis oriented perpendicular to the height of the forming tool. The inner portion is essentially configured as a truncated cone tapering toward the outer portion, and the outer portion includes a contact shape configured to form an engagement shape for rotatably securing and receiving a screw head drive in the screw head. In this way, the screw head bushing according to the present invention can be advantageously formed in a screw blank.

[0016] The inner part of the forming tool according to the invention preferably comprises a truncated conical shell inclined at an angle of 2.5° to 10° relative to the cylindrical shell. According to a preferred embodiment of the forming tool according to the invention, the forming tool further comprises an insertion region arranged between the outer part and the inner part and having an insertion surface, the insertion surface being inclined essentially by 10° relative to the truncated conical base region of the inner part. In this way, simple insertion and centering of the head drive into the head bushing is achieved.

[0017] The contact geometry of the forming tool according to the invention is preferably a Phillips, Torx or slot geometry. Particularly preferably, the contact geometry is a slot geometry that is oriented perpendicular to the height of the forming tool and passes through the forming tool in a second axis different from the first axis. In this way, it is possible to advantageously use a number of different screw drive geometries within the scope of the invention.

[0018] The screw according to the invention comprises a screw head bush according to the invention, which is preferably constructed using a forming tool according to the invention.

[0019] The kit according to the present invention comprises a screw according to the present invention and a screw head drive according to the present invention. The inner part of the screw head drive of the kit according to the present invention has a truncated conical shell with a larger inclination angle relative to the cylindrical shell than the truncated conical shell of the outer part of the screw head bushing of the kit according to the present invention. In this way, a friction fit is achieved between the screw head bushing and the screw head drive, thereby providing a holding force. The holding force allows, for example, the screw to remain fixed in the screw head drive and to be easily placed on a workpiece. This holding force is easily overcome by withdrawing the screw head drive from the screw head bushing. The embodiment of the kit according to the present invention offers the advantage that the holding force acting on the screw can be generated without any additional magnetic elements known in the prior art. [Brief explanation of the drawings]

[0020] [Figure 1a] 1 is a cross-sectional view of a screw head of a screw according to the present invention having a screw head bush according to the present invention. [Figure 1b] 1b is another cross-sectional view of the screw head bushing of FIG. 1a; [Figure 1c] FIG. 1C is a top view of the screw head bushing of FIGS. 1a and 1b; [Figure 2a] 10A and 10B show a variant of another embodiment of a screw head bushing according to the present invention having an engagement shape in the form of a Phillips shape. [Figure 2b] 10A and 10B show a variant of another embodiment of a screw head bushing according to the present invention having an engagement shape in the form of a Phillips shape. [Figure 2c] 10A and 10B show a variant of another embodiment of a screw head bushing according to the present invention having an engagement shape in the form of a Phillips shape. [Figure 3a] 10A and 10B show a variant of another embodiment of a screw head bushing according to the invention having an engagement geometry in the form of a slot geometry; [Figure 3b] 10A and 10B show a variant of another embodiment of a screw head bushing according to the invention having an engagement geometry in the form of a slot geometry; [Figure 3c]10A and 10B show a variant of another embodiment of a screw head bushing according to the invention having an engagement geometry in the form of a slot geometry; [Figure 4a] FIG. 1 is a side view of a screw head drive according to the present invention. [Figure 4b] FIG. 4b is a perspective view of the screw head drive of FIG. 4a. [Figure 4c] FIG. 4c is a top view of the screw head drive of FIGS. 4a and 4b. [Figure 5a] 10A and 10B show a variant of another embodiment of a screw head drive according to the invention having a contact geometry in the form of a Phillips shape. [Figure 5b] 10A and 10B show a variant of another embodiment of a screw head drive according to the invention having a contact geometry in the form of a Phillips shape. [Figure 5c] 10A and 10B show a variant of another embodiment of a screw head drive according to the invention having a contact geometry in the form of a Phillips shape. [Figure 6a] 10A and 10B show a variant of another embodiment of a screw head drive according to the invention having a contact geometry in the form of a slot geometry. [Figure 6b] 10A and 10B show a variant of another embodiment of a screw head drive according to the invention having a contact geometry in the form of a slot geometry. [Figure 6c] 10A and 10B show a variant of another embodiment of a screw head drive according to the invention having a contact geometry in the form of a slot geometry. [Figure 7a] 1 shows a forming tool according to the invention having a contact geometry in the form of a Torx shape; [Figure 7b] 1 shows a forming tool according to the invention having a contact geometry in the form of a Torx shape; [Figure 8a] 1 shows a forming tool according to the invention having a contact geometry in the form of a Phillips shape; [Figure 8b] 1 shows a forming tool according to the invention having a contact geometry in the form of a Phillips shape; [Figure 9a] 1 shows a forming tool according to the invention having a contact geometry in the form of a slot geometry; [Figure 9b]1 shows a forming tool according to the invention having a contact geometry in the form of a slot geometry; [Figure 10a] FIG. 10 is a diagram showing a modified example of the first embodiment of the screw according to the present invention. [Figure 10b] FIG. 10 is a diagram showing a modified example of the first embodiment of the screw according to the present invention. [Figure 11a] 10A and 10B are diagrams showing a modified example of the second embodiment of the screw 1 according to the present invention. [Figure 11b] 10A and 10B are diagrams showing a modified example of the second embodiment of the screw 1 according to the present invention. [Figure 12a] FIG. 10 is a diagram showing a modified example of the third embodiment of the screw 1 according to the present invention. [Figure 12b] FIG. 10 is a diagram showing a modified example of the third embodiment of the screw 1 according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0021] FIG. 1a shows a cross-sectional view of the head of a screw 1 according to the present invention, illustrating the head bushing 2 according to the present invention formed within the screw 1 according to the present invention. The head bushing 2 according to the present invention has an outer portion 3 and an inner portion 4 that continues from the outer portion 3. The outer portion 3 begins at the cover surface 5 of the head of the screw. To screw in the screw 1, the head drive 6 according to the present invention, shown in FIGS. 4a to 4c, is inserted through the outer portion 3 and into the inner portion 4. The outer portion 3 is oriented perpendicular to the depth T of the head bushing 2 and has a larger diameter D than the inner portion 4, at least along the first axis A1 shown in FIG. 1c. This facilitates insertion of the head drive 6 into the head bushing 2. The outer portion 3 essentially has a truncated cone shape tapering toward the inner portion 4. This forms a guide for the head drive 6. The inner portion 4 is configured with an engagement shape for rotatably and securely receiving the head drive 6. Any shape known in the prior art for a screw drive may be provided as an engagement shape within the scope of the present invention. Particularly preferred engagement features are Phillips, Torx, or slotted. A Torx profile is shown in Figures 1-1c. The inventive configuration of the outer and inner parts 3 and 4 allows for improved guiding of the head drive 6 during insertion into the head bushing 2, as well as centering of the head drive 6 within the head bushing 2 before fully engaging the engagement feature. Wear of the engagement feature due to an improperly installed head drive 6 is thus prevented. Figure 1b is another cross-sectional view of the head of a screw 1 having the head bushing 2 according to Figure 1a, rotated by the longitudinal axis L of the head drive 2 relative to Figure 1a. The engagement feature shown in Figures 1a-1c is a Torx profile, and Figure 1a shows the maximum diameter of the Torx profile. Figure 1c is a top view of the screw head according to Figures 1a and 1b, showing the engagement feature in a top view.

[0022] The outer part 3 of the screw head bushing according to the present invention has a truncated conical shell inclined at an angle of 2.5° to 10° relative to the cylindrical shell. The inclination of the truncated conical shell is indicated by the angle α in Figures 1a and 1b. This angle range has proven to be particularly advantageous with regard to the ease of insertion of the screw head drive 6.

[0023] The head bushing 2 preferably further comprises an insertion region 7 arranged between the outer part 3 and the inner part 4 and having an insertion surface 8, as shown in Figures 1a, 1b and 1c. According to a preferred embodiment of the head bushing 2 according to the invention, the insertion surface 8 has an inclination β of essentially 10° relative to the truncated conical base region of the outer part 3 shown in Figure 1a. In this way, it is easier to slide the contact profile of the head drive 6 into the engagement profile of the head bushing 2.

[0024] Figures 2a, 2b and 2c show an alternative form variant of the screw head bushing 2 according to the invention having an engagement shape in the form of a Phillips shape, and Figures 3a, 3b and 3c show another embodiment variant of the screw head bushing 2 according to the invention having an engagement shape in the form of a slot shape.

[0025] As can be seen in figure 3c, the engagement geometry can be in the form of a slot oriented perpendicular to the depth T of the head bushing 2 and passing through the head bushing 2 on a second axis A2 different from the first axis A1. In this way, the advantage is obtained that slot screwdrivers known in the prior art can be used to turn screws provided with the head bushing 2 according to the invention.

[0026] Figures 4a, 4b, and 4c show a screw head drive 6 according to the present invention. The screw head drive 6 according to the present invention includes an outer portion 9 and an inner portion 10 connected to the outer portion 9. The inner portion 10 has a larger diameter D than the outer portion 9 along at least a first axis A1 oriented perpendicular to the height H of the screw head drive 6, as shown in Figure 4c. The inner portion 10 is essentially configured as a truncated cone tapering toward the outer portion 9. The outer portion 9 includes a contact profile configured for rotatably and securely engaging with an engagement profile of the screw head bushing 2. Any shape known in the prior art for screw drives may be provided as a contact profile within the scope of the present invention. This is shown in detail in Figures 4b and 4c. A Torx profile is shown in Figures 4a-4c. Particularly preferred contact profiles are a Phillips profile, a Torx profile, or a slot profile. The screw head drive 6 and the screw head bushing 2 exhibit essentially complementary geometric shapes. The conically tapered inner part 10 of the head drive 6 forms a guide in cooperation with the conical embodiment of the outer part 3 of the head bushing 2, which prevents the head drive 6 from being inserted at an angle with its contact geometry relative to the engagement geometry of the head bushing 2. In this way, improper insertion of the head drive 6 into the head bushing 2 is prevented and slippage of the head drive 6 within the head bushing 2 is avoided.

[0027] The inner part 10 of the screw head drive 6 according to the present invention comprises a truncated conical shell inclined in the range of 2.5° to 10° relative to the cylindrical shell. This inclination is shown in Figure 4a by the inclination angle γ. This angle range has proven to be particularly advantageous with regard to the ease of insertion of the screw head drive 6.

[0028] The head drive 6 preferably further comprises an insertion region 11 arranged between the outer portion 9 and the inner portion 10 and having insertion surfaces 12. These insertion surfaces 12 are shown in Figures 4b and 4c. The insertion surfaces 12 preferably have an inclination δ of essentially 10° relative to the truncated cone base region of the inner portion 10 shown in Figure 4b. In this way, it is easy to slide the contact geometry of the head drive 6 into the engagement geometry of the head bushing 2.

[0029] Figures 5a, 5b and 5c show an alternative embodiment variant of the screw head drive 6 according to the invention having a contact geometry in the form of a Phillips shape, and Figures 6a, 6b and 6c show another embodiment variant of the screw head drive 6 according to the invention having a contact geometry in the form of a slot shape.

[0030] As can be seen from FIG. 6c, the contact shape may be a slot shape that is oriented perpendicular to the height H of the screw head drive 6 and passes through the screw head drive 6 in a second axis A2 that is different from the first axis A1.

[0031] The forming tool 13 according to the invention for forming the screw head bushing 2 in the screw head is used during the manufacture of a screw to form the screw head bushing 2 according to the invention in the screw head of a screw blank. This forming tool 13 has essentially the same shape as the screw head drive 6 according to the invention. The forming tool 13 and the screw head bushing 2 therefore essentially exhibit complementary geometric shapes. Figures 4a, 4b and 4c, 5a, 5b and 5c, and 6a, 6b and 6c therefore also show, by way of example, the top of the forming tool 13 according to the invention.

[0032] The forming tool 13 for forming the screw head bushing 2 in the screw head, like the screw head drive 6, comprises an outer portion 9 and an inner portion 10 contiguous to the outer portion 9, the inner portion 10 having a diameter D greater than that of the outer portion 9, at least along a first axis A1 oriented perpendicular to the height H of the forming tool 13. The inner portion 10 is configured essentially as a truncated cone tapering towards the outer portion 9, the outer portion 10 comprising a contact shape configured to form an engagement shape for rotatably securing and receiving the screw head drive 6 within the screw head. Within the scope of the present invention, any shape known in the prior art for screw drives may be provided as the contact shape or the engagement shape, respectively.

[0033] The inner part 10 of the forming tool 13 preferably comprises a truncated conical shell inclined in the range of 2.5° to 10° relative to the cylindrical shell, this inclination being indicated by the inclination angle γ in Figure 4a. This angle range has proven to be particularly advantageous with regard to the ease of insertion of the screw head drive 6.

[0034] According to a preferred embodiment of the forming tool 13 according to the invention, the forming tool 13 is arranged between the outer part 9 and the inner part 10 and comprises an insertion region 11 with an insertion surface 12. The insertion surface 12 preferably has an inclination δ of essentially 10° relative to the base region of the truncated cone of the inner part 10 shown in Figure 4b. In this way, it is easier to slide the contact profile of the head drive 6 into the engagement profile of the head bushing 2.

[0035] Figures 5a, 5b and 5c show an alternative form variant of a moulding tool 13 according to the invention having a contact geometry in the form of a Phillips shape, and Figures 6a, 6b and 6c show another embodiment variant of a moulding tool 13 according to the invention having a contact geometry in the form of a slot shape.

[0036] As can be seen in FIG. 6c, the contact geometry may be a slot shape that is oriented perpendicular to the height H of the screw head drive 6 and passes through the forming tool 13 on a second axis A2 that is different from the first axis A1.

[0037] Figures 7a to 9b show a forming tool 13 according to the invention in essentially complete form, comprising a portion 14 for mounting the forming tool 13 in a screw manufacturing device. Figures 7a and 7b show a forming tool 13 according to the invention with contact geometries in the form of Torx shapes of two different sizes. Figures 8a and 8b show a forming tool 13 according to the invention with contact geometries in the form of Phillips shapes of two different sizes, and Figures 9a and 9b show a forming tool 13 according to the invention with contact geometries in the form of slot shapes of two different sizes.

[0038] The kit according to the present invention includes a screw 1 according to the present invention and a screw head drive 6 according to the present invention. The inner portion 10 of the screw head drive 6 of the kit according to the present invention has a truncated conical shell with a larger inclination angle γ relative to the cylindrical shell than the truncated conical shell of the outer portion 3 of the screw head bushing 2 of the screw 1 according to the present invention. In this way, when the screw head drive 6 is placed in the screw head bushing 2 of the screw 1, a form fit is achieved between the truncated conical shell of the screw head bushing 2 and the truncated conical shell of the screw head drive 6, and the screw 1 is secured to the screw head drive 6. This has the advantage that the screw 1 can be simply placed on a workpiece without holding it and then screwed in, and furthermore, a magnetic element does not need to be provided in the screw drive head 6. Tests have shown that currently available screw head drives are generally oversized. For example, the TX25 drive known in the prior art has a relatively large drive depth, so that in a wood screw with a diameter of 4 mm, it can transmit a torque that is a multiple of the screw's fractional torque. This knowledge is utilized within the scope of the present invention, since, as a result, the full drive depth is not required to screw in the screw. Therefore, according to the present invention, part of the depth is used for a self-adhesive form-fit to hold the screw 1 in the head drive 6. The different angles α and γ (e.g., 5° for the head bushing 2 and 10° for the head drive 6) of the two truncated conical shells of the head drive 6 and the head bushing 2 result in a very effective form-fit retention of the screw 1 in the head drive 6. The effect of the present invention can be used with any type of screw drive shape. Another advantage is the reliable axial guidance of the head drive 6. In this way, it is impossible to install the head drive 6 on the screw 1 at an angle or diagonally, which minimizes or completely prevents unwanted friction of the head bushing 2 and / or excessive wear of the head drive 6.

[0039] 10a and 10b show a variant of the first embodiment of the screw 1 according to the invention. FIG. 10a is a top view of the screw 1, and FIG. 10b is a cross-sectional view of the screw of FIG. 10a along the line AA. In this variant of the embodiment, the screw 1 rotates circularly around the outer part 3 of the head bushing 2 and has a protrusion extending essentially in the direction of the longitudinal axis of the screw 1. The protrusion 15 preferably has a height of 0.75 mm. The protrusion 15 has the advantage of creating an additional depth T of the head bushing 2, so that the outer part 3 can extend at least partially into the protrusion 15. In this way, the depth of the inner part 4 can be increased, resulting in a larger force-transmitting contact surface between the engagement geometry of the head bushing 2 and the contact geometry of the head drive 6.

[0040] 11a and 11b show a second embodiment variant of the screw 1 according to the invention, which essentially rotates circularly around the outer part 3 of the screw head bushing 2 and has a cover surface 16 that slopes downward towards the radial outside of the screw 2. The cover surface 16 slopes downward over a height of preferably 0.75 mm. FIG. 11a shows a top view of the screw 1, and FIG. 11b shows a cross-section of the screw of FIG. 11a along the line AA. The shape of the cover surface 13 has the technical effect of creating an additional depth T of the screw head bushing 2, just like in the first embodiment variant of the screw 1 according to the invention.

[0041] 12a and 12b show a third embodiment of a screw 1 according to the invention. Fig. 12a shows a top view of the screw 1, and Fig. 12b shows a cross-section of the screw of Fig. 12a along the line AA. According to this embodiment, the screw 1 has an outer surface 17 that extends in the longitudinal direction of the screw 1 and rotates essentially completely around the outer part 3 of the screw head bushing 2. The outer surface 17 preferably has a height of 1.31 mm. The outer surface 17 also forms an additional depth T of the screw head bushing 2, further providing additional mechanical stability of the outer part 3.

[0042] TX25 drives known in the prior art have head bushing depths T in the range of 1.9 mm to 2.3 mm. These depths T are typically obtained for head bushing diameters in the range of 5 mm and head diameters of 9.5 mm to 10 mm, resulting in head heights of 4.8 mm to 5.2 mm.

[0043] The screw 1 according to the invention has a head height in the range of 5.75 mm according to the prescribed screw size, and the depth of the engagement shape of the inner part 4 is preferably about 1.95 mm. In this case, the head diameter of the screw 1 is about 10 mm. For any other screw size, these values ​​are increased or decreased accordingly.

Claims

1. A kit comprising a screw (1) having a screw head bush (2), the screw head bush (2) having an outer portion (3) and an inner portion (4) following the outer portion (3), the outer portion (3) of the screw head bush (2) having at least a first axis (A) oriented perpendicular to a depth (T) of the screw head bush (2). １ ) has a diameter (D) greater than an inner portion (4) of the head bushing (2), the outer portion (3) of the head bushing (2) is configured essentially as a truncated cone tapering towards the inner portion (4) of the head bushing (2), the inner portion (4) of the head bushing (2) is configured as an engaging shape for rotatably and fixedly receiving a head drive (6), the kit further comprises a head drive (6) having an outer portion (9) and an inner portion (10) continuous from the outer portion (9), the inner portion (10) of the head drive (6) being oriented along at least a first axis (A) perpendicular to a height (H) of the head drive (6). １ ) has a larger diameter (D) than the outer portion (9) of the head drive (6), the inner portion (10) of the head drive (6) is configured essentially as a truncated cone tapering towards the outer portion (9) of the head drive (6), the outer portion (9) of the head drive (6) has a contact shape configured to rotatably and fixedly engage with an engagement shape of the head bushing (2), the inner portion (10) of the head drive (6) has a larger inclination angle (γ) with respect to a cylindrical shell than the truncated cone shell of the outer portion (3) of the head bushing (2) of the screw (1), providing a friction fit between the head bushing (2) of the screw (1) and the head drive (6).

2. 2. A kit according to claim 1, characterized in that the outer part (3) of the screw head bush (2) comprises a truncated conical shell inclined at an angle ranging from 2.5° to 10° relative to the cylindrical shell.

3. 3. The kit according to claim 1 or 2, characterized in that the screw head bush (2) is arranged between the outer part (3) and the inner part (4) and comprises an insertion region (11) with an insertion surface (12), the insertion surface (12) having an inclination of essentially 10° with respect to a frustoconical base region of the outer part (3).

4. 4. The kit according to claim 1, wherein the engagement shape is a Phillips shape, a Torx shape or a slot shape.

5. The engagement shape is oriented perpendicular to the depth (T) of the screw head bushing (2) and is aligned with the first axis (A １ ) and a second axis (A ２ 4. A kit according to claim 1, wherein the screw head bushing (2) is in the form of a slot passing through the screw head bushing (2).

6. 6. The kit according to any one of claims 1 to 5, characterized in that the inner part (10) of the screw head drive (6) comprises a truncated conical shell inclined at an angle ranging from 2.5° to 10° relative to the cylindrical shell.

7. 7. The kit according to claim 1, wherein the head drive (6) comprises an insertion region (11) arranged between the outer part (9) and the inner part (10) and having an insertion surface (12), the insertion surface (12) having an inclination of essentially 10° relative to a frustoconical base region of the inner part.

8. 8. The kit according to claim 1, wherein the contact shape is a Phillips shape, a Torx shape or a slot shape.

9. The contact geometry is oriented perpendicular to the height (H) of the screw head drive (6) and is aligned with the first axis (A １ ) and a second axis (A ２ 9. The kit according to claim 1, wherein the screw head drive (6) is in the form of a slot passing through the screw head drive (6).

10. 2. The kit according to claim 1, characterized in that the screw (1) has a protrusion (15) which rotates circularly around the outer part (3) of the screw head bush (2) and extends essentially in the direction of the longitudinal axis of the screw (1).

11. 2. The kit according to claim 1, characterized in that the screw (1) rotates circularly around the outer part (3) of the screw head bushing (2) and has a cover surface (16) that descends radially outward of the screw (2).

12. 2. The kit according to claim 1, characterized in that the screw (1) has an outer surface (17) extending in the longitudinal direction of the screw (1) and rotating essentially completely around the outer part (3) of the screw head bushing (2).

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